Polycarbonate resin composition

ABSTRACT

For making a polycarbonate resin resistant to flames with any of non-halogen and non-phosphorus compounds, provided is a polycarbonate resin composition having good flame retardancy and having good impact resistance, high stiffness and good chemical resistance. The flame-retardant polycarbonate resin composition comprises a resin mixture of (A) from 1 to 99% by weight of a polycarbonate and (B) from 1 to 99% by weight of a thermoplastic polyester, and contains, relative to 100 parts by weight of the resin mixture, (C) from 0.01 to 3 parts by weight of a polyfluoro-olefin resin, and (D) from 1 to 400 parts by weight of a polycarbonate-polyorganosiloxane copolymer and/or (E) from 0.1 to 10 parts by weight of a functional silicone compound.

TECHNICAL FIELD

The present invention relates to a polycarbonate resin composition, moreprecisely, to a polycarbonate resin composition not containing halogenand phosphorus but containing a minor additive to exhibit good flameretardancy and have good impact resistance, high stiffness, good meltflowability and good chemical resistance.

BACKGROUND ART

As having the advantages of impact resistance, heat resistance and goodelectric properties, polycarbonate resins have many applications invarious fields of, for example, OA (office automation) appliances,information and communication appliances, other electric and electronicappliances for industrial use and household use, automobile parts andbuilding materials. As a rule, polycarbonate resins areself-extinguishable. However, some fields of typically OA appliances,information and communication appliances, and other electric andelectronic appliances for industrial use and household use require highflame retardancy, for which are used various flame retardants to improvetheir flame retardancy.

For improving the flame retardancy of polycarbonate resins,halogen-containing flame retardants such as bisphenol A halides andhalogenated polycarbonate oligomers have been used along with a flameretardation promoter such as antimony oxide, as their flame-retardingability is good. However, with the recent tendency toward safety livingwith polycarbonate resin products and toward environmental protectionfrom discarded and incinerated wastes of the products, the marketrequires flame retardation of polycarbonate resins with non-halogenflame retardants. Given that situation, polycarbonate resin compositionswith phosphorus-containing organic flame retardants, especially organicphosphate compounds that are non-halogen flame retardants have beenproposed, and their flame retardancy is good. Such phosphorus-containingorganic flame retardants serve also as a plasticizer, and variousmethods of using them for making polycarbonate resins resistant toflames have been proposed.

However, in order to make polycarbonate resins have good flameretardancy by adding thereto an organic phosphate compound, a relativelylarge amount of the compound must be added to the resins. In general,polycarbonate resins require relatively high molding temperatures, andtheir melt viscosity is high. Therefore, for molding them intothin-walled and large-sized moldings, the molding temperature will haveto be more higher. For these reasons, organic phosphate compounds oftencause some problems when added to such polycarbonate resins, thoughtheir flame-retarding ability is good. For example, organic phosphatecompounds often corrode molds used for molding resins containing them,and generate gas to have some unfavorable influences on the workingenvironments and even on the appearance of the moldings. Another problemwith organic phosphate compounds is that, when the moldings containingthem are left under heat or in high-temperature and high-humidityconditions, the compounds lower the impact strength of the moldings andyellow the moldings. In addition, polycarbonate resin compositionscontaining organic phosphate compounds are not stable under heat, andtherefore do not meet the recent requirement for recycling resinproducts. This is still another problem with organic phosphatecompounds.

On the other hand, for machine parts which will be often stained withoil or copying ink having scattered therearound and for products thatwill be coated with grease or the like, resin materials are furtherrequired to have good chemical resistance in addition to flameretardancy.

To meet the market requirements, proposed is another technique of addingsilicone compounds to polycarbonate resins to make the resins have flameretardancy. In this, silicone compounds added to the resins do not givetoxic gas when fired. For example, (1) Japanese Patent Laid-Open No.139964/1998 discloses a flame retardant that comprises a silicone resinhaving a specific structure and a specific molecular weight.

(2) Japanese Patent Laid-Open Nos. 45160/1976, 318069/1989, 306265/1994,12868/1996, 295796/1996, and Japanese Patent Publication No. 48947/1991disclose silicone-containing, flame-retardant polycarbonate resincompositions. The flame retardancy level of the products in (1) is highin some degree, but the impact resistance thereof is often low. Thetechnology of (2) differs from that of (1) in that the silicones used in(2) do not act as a flame retardant by themselves, but are for improvingthe dripping resistance of resins, and some examples of silicones forthat purpose are mentioned. Anyhow, in (2), the resins indispensablyrequire an additional flame retardant of, for example, organic phosphatecompounds or metal salts of Group 2 of the Periodic Table. Anotherproblem with the flame-retardant polycarbonate resin compositions in (2)is that the flame retardant added thereto worsens the moldability andeven the physical properties of the resin compositions and theirmoldings.

Also known is a flame-retardant polycarbonate resin composition thatcomprises a polycarbonate resin, a polycarbonate-polyorganosiloxanecopolymer-containing resin and a fibril-forming polytetrafluoroethylene(Japanese Patent Laid-Open No. 81620/1996). Even though itspolyorganosiloxane content is low, falling within a defined range, thecomposition exhibits good flame retardancy. Though its flame retardancyis good, however, the composition is problematic in that its impactresistance intrinsic to polycarbonate resins is often low.

For improving the chemical resistance of polycarbonate resins, it isgenerally known to add a thermoplastic polyester to the resins. Forexample, Japanese Patent Laid-Open No. 181265/1999 discloses apolycarbonate resin composition prepared by adding a polyester resin, analkali metal or alkaline earth metal perfluoroalkanesulfonate, afluororesin and a silicone, to a polycarbonate resin. However, since itshigh-temperature thermal stability in dwell time in an extruder or thelike is often poor, the resin composition is difficult to recycle.

The present invention has been made in the current situation as above,and its object is to provide a non-halogen and non-phosphorus,flame-retardant polycarbonate resin composition of which the flameretardancy is good and which has good impact resistance, high stiffness,good melt flowability and good chemical resistance.

DISCLOSURE OF THE INVENTION

I, the present inventor have assiduously studied, and, as a result, havefound that, when a thermoplastic polyester, a polyfluoro-olefin resin,and a polycarbonate-polyorganosiloxane copolymer and/or a specificsilicone compound are added to a polycarbonate resin, then theabove-mentioned object of the invention can be effectively attained. Onthe basis of this finding, we have completed the present invention.

Specifically, the invention is summarized as follows:

1. A polycarbonate resin composition which comprises a resin mixture of(A) from 1 to 99% by weight of a polycarbonate and (B) from 1 to 99% byweight of a thermoplastic polyester, and contains, relative to 100 partsby weight of the resin mixture, (C) from 0.01 to 3 parts by weight of apolyfluoro-olefin resin, and (D) from 1 to 400 parts by weight of apolycarbonate-polyorganosiloxane copolymer and/or (E) from 0.1 to 10parts by weight of a functional silicone compound, and of which thesilicone content derived from the component (D) and/or the component (E)falls between 0.5 and 10% by weight of the composition.

2. The polycarbonate resin composition of above 1, which furthercontains (F) from 1 to 50 parts by weight of an inorganic filler.

3. The polycarbonate resin composition of above 1 or 2, wherein thefunctional silicone compound for the component (E) has a basic structureof a general formula (1):

R¹ _(a) R₂ ^(b)SiO_((4−a−b)/2)  (1)

wherein R¹ indicates a functional group, R² indicates a hydrocarbonresidue having from 1 to 12 carbon atoms, and a and b are numberssatisfying the relations of 0<a≦3, 0≦b<3, and 0<a+b≦3.

4. The polycarbonate resin composition of any of above 1 to 3, whereinthe functional group in the functional silicone compound for thecomponent (E) is selected from an alkoxy group, a vinyl group, ahydrogen residue and an epoxy group.

5. The polycarbonate resin composition of any of above 1 to 4, whereinthe functional group in the functional silicone compound for thecomponent (E) is a methoxy group or a vinyl group.

6. The polycarbonate resin composition of any of above 1 to 5, whereinthe polyfluoro-olefin resin for the component (C) is a fibril-formingpolytetrafluoroethylene having a mean molecular weight of at least500,000.

7. The polycarbonate resin composition of any of above 1 to 6, whereinthe polycarbonate for the component (A) has a viscosity-averagemolecular weight of from 15,000 to 20,000.

8. The polycarbonate resin composition of any of above 2 to 7, whereinthe inorganic filler for the component (F) is talc having a meanparticle size of from 0.2 to 20 μm.

9. Housings or parts of electric and electronic appliances, whichcomprise the polycarbonate resin composition of any of above 1 to 8.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a tool for holding a test piece thereonfor evaluating the grease resistance of the polycarbonate resincomposition of the invention.

BEST MODES OF CARRYING OUT THE INVENTION

The invention is described in detail hereinunder.

(A) Polycarbonate:

The polycarbonate (PC) for the component (A) in the polycarbonate resincomposition of the invention is not specifically defined, and may be anyand every one known in the art. Generally used herein are aromaticpolycarbonates to be produced through reaction of diphenols andcarbonate precursors. For example, herein used are polycarbonatesproduced by reacting a diphenol and a carbonate precursor in a solutionmethod or in a melt method, such as those produced through reaction of adiphenol and phosgene or through interesterification of a diphenol and adiphenyl carbonate.

Various diphenols are usable, typically including2,2-bis(4-hydroxyphenyl)propane [bisphenol A],bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane,2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 4,4′-dihydroxydiphenyl,bis(4-hydroxyphenyl)cycloalkanes, bis(4-hydroxyphenyl) oxide,bis(4-hydroxyphenyl) sulfide, bis(4-hydroxyphenyl) sulfone,bis(4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl) ether, and bis(4-hydroxyphenyl) ketone.

For the diphenols for use herein, especially preferred arebis(hydroxyphenyl)alkanes, more preferably, those consisting essentiallyof bisphenol A. Other examples of diphenols usable herein arehydroquinone, resorcinol and catechol. The diphenols mentioned hereinmay be used either singly or as combined.

The carbonate precursors for use in the invention include, for example,carbonyl halides, carbonyl esters, and haloformates, concretely,phosgene, dihaloformates of diphenol, diphenyl carbonate, dimethylcarbonate, and diethyl carbonate.

The polycarbonate resin for the component (A) may have a branchedstructure, for which the branching agent includes, for example,1,1,1-tris(4-hydroxyphenyl)ethane,α,α′,α″-tris(4-hyroxyphenyl)-1,3,5-triisopropylbenzene, phloroglucine,trimellitic acid, and isatin-bis(o-cresol). For controlling themolecular weight of the polycarbonate resin, for example, employable arephenol, p-t-butylphenol, p-t-octylphenol, and p-cumylphenol.

The polycarbonate resin for use in the invention may be a copolymer suchas a polyester-polycarbonate resin to be produced through polymerizationof polycarbonate in the presence of an ester precursor, such as adifunctional carboxylic acid (e.g., terephthalic acid) or itsester-forming derivative. Various types of different polycarbonateresins may be mixed to give mixed polycarbonate resins for use in theinvention.

The viscosity-average molecular weight of the polycarbonate resin to beused in the invention generally falls between 10,000 and 50,000, butpreferably between 13,000 and 35,000, more preferably between 15,000 and20,000. The viscosity of the resin in a methylene chloride solution at20° C. is measured with an Ubbelohde's viscometer, and the intrinsicviscosity [η] thereof is derived from it. The viscosity-averagemolecular weight (Mv) of the resin is calculated according to thefollowing equation:

[η]=1.23×10⁻⁵ Mv ^(0.83).

(B) Thermoplastic Polyester:

Various types of thermoplastic polyesters are usable for the component(B) in the invention. For the component (B), specially preferred arepolyester resins obtained through polycondensation of a difunctionalcarboxylic acid component and an alkylene glycol component. For thedifunctional carboxylic acid component and the alkylene glycolcomponent, mentioned are the following.

For the difunctional carboxylic acid component, mentioned are aromaticdicarboxylic acids including, for example, terephthalic acid,isophthalic acid and naphthalenedicarboxylic acid. Of those, preferredis terephthalic acid. Not interfering with the effect of the invention,the component may contain any other difunctional carboxylic acids, whichare, for example, aliphatic carboxylic acids such as oxalic acid,malonic acid, adipic acid, suberic acid, azelaic acid, sebacic acid anddecanedicarboxylic acid. In general, the proportion of the additionaldicarboxylic acids is preferably at most 20 mol % of the total amount ofthe dicarboxylic acid component.

The alkylene glycol component is not specifically defined. For it,concretely, usable are aliphatic diols having from 2 to 10 carbon atoms,such as ethylene glycol, propylene-1,2-glycol, propylene-1,3-glycol,butylene-1,4-glycol, butylene-2,3-glycol, hexane-1,6-diol,octane-1,8-diol, neopentyl glycol and decane-1,10-diol. Of those,preferred are ethylene glycol and butylene glycols.

The thermoplastic polyester for the component (B) may be produced in anyordinary method of polycondensation in the presence or absence of apolycondensation catalyst that contains any of titanium, germanium andantimony. For example, polyethylene terephthalate is generally producedby esterifying terephthalic acid with ethylene glycol ortransesterifying a lower alkyl ester such as dimethyl terephthalate withethylene glycol to prepare a glycol terephthalate and/or its oligomer inthe first stage reaction followed by further polymerizing the glycolester and/or its oligomer into a polymer having an increased degree ofpolymerization in the second stage reaction.

The polycarbonate resin composition of the invention comprises apolycarbonate for the component (A) and a thermoplastic polyester forthe component (B), in which the combination of the two componentsimproves the melt flowability and the chemical resistance of the resincomposition. The blend ratio of the component (A) to the component (B)in the resin mixture is such that the polycarbonate (A) accounts forfrom 1 to 99% by weight, preferably from 50 to 90% by weight of themixture, and the thermoplastic polyester (B) accounts for from 1 to 99%by weight, preferably from 10 to 50% by weight thereof.

(C) Polyfluoro-olefin Resin:

The polycarbonate resin composition of the invention contains apolyfluoro-olefin resin which is for preventing the resin moldings frombeing melted to drip when fired. The polyfluoro-olefin resin isgenerally a polymer or copolymer having a fluoroethylene structure. Forexample, it includes difluoroethylene polymers, tetrafluoroethylenepolymers, tetrafluoroethylene-hexafluoropropylene copolymers, andcopolymers of tetrafluoroethylene and fluorine-free ethylenic monomers.Preferred foruse herein ispolytetrafluoroethylene (PTFE), and its meanmolecular weight is preferably at least 500,000, more preferably from500,000 to 10,000,000. Any and every type of polytetrafluoroethyleneknown in the art is usable in the invention.

Especially preferred for use herein is polytetrafluoroethylene havingthe ability to form fibrils, as it is more effective for preventing theresin melt from dripping. The fibril-forming polytetrafluoroethylene(PTFE) usable herein is not specifically defined. For example, PTFE ofType 3 that is grouped according to the ASTM Standard is used herein.Commercial products of such PTFE are available, including, for example,Teflon 6-J (from Mitsui-DuPont Fluorochemical), Polyflon D-1, PolyflonF-103 and Polyflon F-201 (all from Daikin Industry), and CD076 (fromAsahi IC Fluoropolymers).

Except PTFE of Type 3 as above, others are also usable herein,including, for example, Argoflon 5 (from Montefluos), Polyflon MPA,Polyflon FA-100 (both from Daikin Industry), etc. One or more of thesepolytetrafluoroethylenes (PTFE) can be used either singly or ascombined. The fibril-forming polytetrafluoroethylene (PTFE) such asthose mentioned above can be obtained, for example, by polymerizingtetrafluoroethylene in an aqueous medium in the presence of sodium,potassium or ammonium peroxydisulfide therein, under a pressure of from1 to 100 psi at a temperature falling between 0 and 200° C, preferablybetween 20 and 100° C.

The content of the component (C) in the resin composition falls between0.01 and 3 parts by weight, preferably between 0.05 and 1 part by weightor between 0.05 and 2 parts by weight, relative to 100 parts by weightof the resin mixture of the components (A) and (B) therein. If it is toosmall, the dripping resistance of the resin composition will be notenough for the intended flame retardancy of the composition. However,even if its content is larger than the defined range, thepolyfluoro-olefin resin added could no more augment its effect, and sucha large amount of the polyfluoro-olefin resin, if added to the resincomposition, will have some negative influences on the impact resistanceand the outward appearance of the moldings of the composition.Therefore, the amount of the polyfluoro-olefin resin to be added to theresin composition may be suitably determined, depending on the necessaryflame retardancy of the composition, for example, based on V-0, V-1 orV-2 in UL-94, and depending on the amount of the other constituentcomponents.

The polycarbonate resin composition of the invention contains thecomponent (D) and/or the component (E) in addition to theabove-mentioned components (A) to (C).

(D) Polycarbonate-polyorganosiloxane Copolymer:

The polycarbonate-polyorganosiloxane copolymer (hereinafter referred toas PC-polyorganosiloxane copolymer) for the component (D) in theinvention is a polymer comprising a polycarbonate moiety and apolyorganosiloxane moiety. The PC-polyorganosiloxane copolymer may beproduced, for example, through interfacial polycondensation of apolycarbonate oligomer and a reactive group-terminatedpolyorganosiloxane (e.g., polydimethylsiloxane, polydiethylenesiloxane,polymethylphenylsiloxane, polydiphenylsiloxane) which are dissolved in asolvent such as methylene chloride with an aqueous solution of bisphenolA in sodium hydroxide added thereto, in the presence of a catalyst suchas triethylamine.

Preferably, the degree of polymerization of the polycarbonate moiety ofthe PC-polyorganosiloxane copolymer falls between 3 and 100 or so. Alsopreferably, the degree of polymerization of the polyorganosiloxanemoiety of the copolymer falls between 2 and 500 or so. Thepolyorganosiloxane content of the PC-polyorganosiloxane copolymergenerally falls between 0.5 and 30% by weight, but preferably between 1and 20% by weight. The viscosity-average molecular weight of thePC-polyorganosiloxane copolymer for the component (D) generally fallsbetween 5,000 and 100,000, but preferably between 10,000 and 30,000.This may be measured in the same manner as that for the polycarbonatementioned above.

The resin composition contains from 1 to 400 parts by weight, preferablyfrom 5 to 330 parts by weight of the component (D), relative to 100parts by weight of the resin mixture of the components (A) and (B)therein. If the amount of the component (D) in the resin composition notcontaining the component (E) is too small, the resin composition is notsatisfactorily resistant to flames; but even if too large, the copolymeradded could no more augment its effect.

In the polycarbonate resin composition comprising the components (A),(B), (C) and (D), the content of the component (D) preferably fallsbetween 1 and 400 parts by weight, more preferably between 5 and 330parts by weight. Also in the resin composition comprising the components(A), (B), (C), (D) and (E), the content of the component (D) preferablyfalls between 1 and 400 parts by weight, more preferably between 5 and330 parts by weight.

(E) Functional Silicone Compound:

The functional silicone compound for the component (E) in the inventionis a functional (poly)organosiloxane. Preferably, it is a polymer orcopolymer having a basic structure of the following general formula (1):

R¹ _(a) ²R_(b)SiO_((4−a−b)/2)  (1)

wherein R¹ indicates a functional group, R² indicates a hydrocarbonresidue having from 1 to 12 carbon atoms, and 0<a≦3, 0≦b<3, and 0<a+b≦3.

The functional group for R¹ includes, for example, an alkoxy group, anaryloxy group, a polyoxyalkylene group, a hydrogen residue, a hydroxylgroup, a carboxyl group, a silanol group, an amino group, a mercaptogroup, an epoxy group, and a vinyl group, of those, preferred are analkoxy group, a hydrogen group, a vinyl group, and an epoxy group; andmore preferred are a methoxy group and a vinyl group. Preferred examplesof the hydrocarbon residue having from 1 to 12 carbon atoms for R² are amethyl group and a phenyl group. Preferred ranges of a, b and (a+b) areas follows: 0.2≦a≦2.5, 0≦b≦2.5, and 0.2≦a+b≦3.

The silicone compound for the component (E) may have a plurality ofdifferent functional groups; or a plurality of silicone compounds havingdifferent functional groups may be combined for the component (E).

In the basic structure of the functional silicone compound, the ratio offunctional group (R¹)/hydrocarbon residue (R²) generally falls between0.1 and 3 or so, but preferably between 0.3 and 2 or so.

The functional silicone compound for the component (E) is liquid orpowdery, but is preferably well dispersible in the other constituentcomponents while they are kneaded in melt. One preferred example of thecompound is liquid and has a viscosity at room temperature of from 10 to500,000 cst or so. The polycarbonate resin composition containing thecomponent (E) of the invention is characterized in that the componentuniformly disperses therein even when it is liquid, and bleeds littleout of the composition being molded and out of the moldings of thecomposition.

The resin composition may contain from 0.1 to 10 parts by weight,preferably from 0.2 to 5 parts by weight or from 2 to 5 parts by weightof the functional silicone compound, relative to 100 parts by weight ofthe resin mixture of the components (A) and (B) therein. If the contentof the compound therein is smaller than 0.1 parts by weight, the resincomposition, if not containing the component (D), could not be resistantto flames; but even if larger than 10 parts by weight, the compoundcould no more augment its effect.

In the polycarbonate resin composition comprising the components (A),(B), (C) and (E), the content of the component (E) preferably fallsbetween 0.2 and 5 parts by weight, more preferably between 0.5 and 5parts by weight. Also in the composition comprising the components (A),(B), (C), (D) and (E), the content of the component (E) preferably fallsbetween 0.2 and 5 parts by weight, more preferably between 0.5 and 5parts by weight.

The polycarbonate resin composition of the invention is preferably socontrolled that the silicone content derived from the components (D)and/or the component (E) thereof falls between 0.5 and 10% by weight,more preferably between 0.7 and 5% by weight of the composition. If thesilicone content is smaller than 0.5% by weight, the resin compositionwill be poorly resistant to flames; but if larger than 10% by weight,the impact resistance and the heat resistance of the composition willlower. The silicone content derived from the component (D) and/or thecomponent (E) corresponds to the polyorganosiloxane content of thecomponent (D) and/or the component (E).

(F) Inorganic Filler:

The resin composition comprising the components (A) to (C), and (D)and/or (E) attains the object of the invention. If desired, it mayfurther contain an inorganic filler (F) which is for enhancing thestiffness and the flame retardancy of its moldings.

The inorganic filler includes, for example, talc, mica, kaolin,diatomaceous earth, calcium carbonate, calcium sulfate, barium sulfate,glass fibers, carbon fibers, and potassium titanate fibers. Especiallypreferred for use herein are tabular fillers of, for example, talc andmica, and fibrous fillers. Talc is a magnesium silicate hydrate, and itscommercial products are preferably used herein. The inorganic tabularfiller such as talc for use herein preferably has a mean particle sizeof from 0.1 to 50 μm, more preferably from 0.2 to 20 μm. The inorganicfiller, especially talc, if in the resin composition, is effective forfurther enhancing the stiffness of the moldings of the composition, and,as the case may be, it will be able to reduce the amount of the siliconecompound to be in the composition.

The content of the inorganic filler (F) in the resin composition mayfall between 1 and 50 parts by weight, preferably between 2 and 30 partsby weight, relative to 100 parts by weight of the resin mixtures of thecomponents (A) and (B) therein. If its amount is too small, theinorganic filler added could not satisfactorily exhibit its effect ofenhancing the stiffness and the flame retardancy of the moldings of thecomposition; but if too large, the impact resistance of the moldingswill lower and the melt fluidity of the composition will lower. Theamount of the inorganic filler to be in the resin composition may besuitably determined, depending on the necessary properties of themoldings and the moldability of the composition, especially on thethickness of the moldings and the flowability of the composition.

In addition to the above-mentioned components, an elastomer may be addedto the polycarbonate resin composition of the invention for furtherenhancing the impact resistance of the moldings of the composition.Preferred for that purpose is a core/shell-type elastomer. Preferably,the amount of the elastomer to be added falls between 0.5 and 10 partsby weight relative to 100 parts by weight of the resin mixture of thecomponents (A) and (B) in the resin composition.

The polycarbonate resin composition of the invention may contain, inaddition to the above-mentioned components, any additives that aregenerally added to ordinary thermoplastic resins, if desired. Theadditives include, for example, phenolic, phosphorus-containing orsulfur-containing antioxidants, antistatic agents, permanent antistaticagents such as polyamide-polyether block copolymers, benzotriazole-typeor benzophenone-type UV absorbents, hindered amine-type lightstabilizers (weather-proofing agents), plasticizers, microbicides,compatibilizers, and colorants (dyes, pigments). For their amount, theoptional additives that may be in the polycarbonate resin composition ofthe invention are not specifically defined, provided that they do notinterfere with the properties of the composition.

A method for producing the polycarbonate resin composition of theinvention is described. The composition may be produced by mixing,melting and kneading the components (A) to (E) in the predeterminedratio as above, optionally along with the optional component such as (F)and additives as above in any desired ratio. Formulating and kneadingthe constituent components into the intended resin composition may beeffected in any known manner, for example, by pre-mixing them in anordinary device, such as a ribbon blender or a drum tumbler, followed byfurther kneading the resulting pre-mix in a Henschel mixer, a Banburymixer, a single-screw extruder, a double-screw extruder, a multi-screwextruder, or a cokneader. The temperature at which the components aremixed and kneaded generally falls between 240 and 300° C. For moldingthe melt mixture, preferably used is an extrusion molding machine, morepreferably a vented extruder. Other constituent components than thepolycarbonate resin may be previously mixed to prepare a master batch,and it may be added to the polycarbonate resin.

Having been prepared by mixing and kneading the constituent componentsin the manner noted above, the polycarbonate resin composition of theinvention may be pelletized, and the resulting pellets may be moldedinto various moldings through injection molding, injection compressionmolding, extrusion molding, blow molding, pressing, vacuum forming orfoaming. The composition is especially favorable to injection molding orinjection compression molding to give moldings. For injection molding ofthe composition, preferred is a gas-assisted molding method so as toimprove the appearance of the moldings formed, especially to preventsinking marks in the moldings and to reduce the weight of the moldings.

The polycarbonate resin composition of the invention satisfies thestandard of UL94/V-0 (1.5 mm) or UL94/V-1 (1.5 mm), and its moldings arefavorable to various housings and parts of electric and electronicappliances, such as duplicators, facsimiles, televisions, radios, taperecorders, video decks, personal computers, printers, telephones,information terminals, refrigerators, and microwave ovens. The moldingshave still other applications, for example, for automobile parts.

The invention is described more concretely with reference to thefollowing Examples and Comparative Examples, which, however, are notintended to restrict the scope of the invention.

EXAMPLES 1 to 5, AND COMPARATIVE EXAMPLES 1 to 4

The components shown in Table 1 were blended in the ratio indicatedtherein (all in terms of parts by weight), fed into a venteddouble-screw extruder (TEM35 from Toshiba Kikai), melted and kneadedtherein at 280° C., and then pelletized. To all compositions of Examplesand Comparative Examples, added were 0.2 parts by weight of Irganox 1076(from Ciba Specialty Chemicals, octadecyl3-(3,5-t-butyl-4-hydroxyphenyl)propionate) and 0.1 parts by weight ofAdekastab C (from Asahi Denka Industry, diphenyl(2-ethylhexyl)phosphite) both serving as an antioxidant. The resulting pellets weredried at 120° C. for 12 hours, and then molded into test pieces in amode of injection molding at 270° C. The mold temperature was 80° C.These test pieces were tested for their properties in various testmethods, and their data obtained are given in Table 1.

The molding materials used and the test methods employed are mentionedbelow.

(A) Polycarbonate:

PC-1: bisphenol A polycarbonate resin, Toughlon A1900 (from IdemitsuPetrochemical), having an MI of 20 g/10 min (at 300° C. under a load of1.2 kg), and a viscosity-average molecular weight of 19,000.

(B) Thermoplastic Polyester:

PET: polyethylene terephthalate, Dianite MA523 (from Mitsubishi Rayon).

PBT: polybutylene terephthalate, Toughpet N1000 (from Mitsubishi Rayon).

(C) Polyfluoro-olefin Resin:

PTFE: CD076 (from Asahi Fluoropolymers, having a mean molecular weightof 3,000,000).

(D) Polycarbonate-polyorganosiloxane Copolymer:

PC-PDMS: bisphenol A polycarbonate-polydimethylsiloxane (PDMS)copolymer, having an MI of 45 g/10 min (at 300° C. under a load of 1.2kg), a PDMS chain length (n) of 30, a PDMS content of 4% by weight, anda viscosity-average molecular weight of 20,000 (produced in ProductionExample 3-1 (A₁) in Japanese Patent Laid-Open No. 81260/1996).

(E) Functional Silicone Compound:

Silicone-1: methylphenylsilicone with vinyl and methoxy groups, KR219(from Shin-etsu Chemical Industry), having a viscosity of 18 cst (at 23°C.). This corresponds to formula (1) in which R¹/R²=0.67, a=1 and b=1.5.

Silicone-2: methoxy group-having dimethylsilicone, KC-89 (from Shin-etsuChemical Industry), having a viscosity of 20 cst (at 23° C.). Thiscorresponds to formula (1) in which R¹/R²=1.0, a=1 and b=1.

Silicone-3 (for comparison): dimethylsilicone, SH200 (from Toray DowCorning), having a viscosity of 350 cst (at 23° C.)

(F) Inorganic Filler:

Talc: FFR (from Asada Milling), having a mean particle size of 0.7 μm.

(G) Other Component:

Elastomer: core/shell-type, grafted rubber-like elastomer, MetablenS2001 (from Mitsubishi Rayon).

[Test Methods]

(1) Melt Flowability:

MI (melt index) of each sample is measured at 300° C. under a load of1.2 kg, according to JIS K7210.

(2) IZOD Impact Strength:

Measured according to ASTMD256. The temperature is 23° C., and thethickness of samples is ⅛ inches. The data are in terms of kJ/m².

(3) Flexural Modulus:

Measured according to ASTM D-790. The temperature is 23° C., and thethickness of samples is 4 mm. The data are in terms of MPa.

(4) Grease Resistance:

Measured according to a chemical resistance test method (for measuringthe critical deflection of a test sample on a quarter oval tool).

Concretely, a test sample (having a thickness of 3 mm) is fixed on aquarter oval tool as in FIG. 1 (showing a perspective view of the tool),Albanian grease (from Showa Shell Petroleum) is applied thereto, andthis is kept as such for 48 hours. The shortest length (X) of the toolon which the sample has been cracked is read, and the criticaldeflection (%) of the sample is obtained according to the followingequation.

Critical Deflection (%)=b/2a²×[1−(1/a²−b²/a⁴)X²]^(−3/2)t, in which tindicates the thickness of the test sample.

(5) Flame Retardancy:

Tested according to the UL94 combustion test. Samples tested have athickness of 1.5 mm.

(6) Thermal Stability in Dwell Time (300° C., 20 mm):

The resin pellets are injection-molded into square plates in the samemanner as above. In this process, the cylinder temperature in theinjection-molding machine (Toshiba Kikai's 100EN) is kept flat (that is,the temperature in the cylinder is kept constant). The square platesthus molded have an outline size of 80 mm×80 mm and a thickness of 3.2mm. Under the defined molding condition, the pellets are molded for 10shots. After the necessary measurement, the resin melt is left in thecylinder for 20 minutes. Next, the resin pellets are injection-molded inthe second run in the same manner as previously, and the first-shotsamples are visually evaluated for their appearance.

In Table 1, “good” means that no visual difference in color was foundbetween the first-shot samples in the second run and ordinary shotsamples, and that the first-shot samples in the second run had no silvermarks. “Silver” means that streaks (silver marks) were formed in thesurface of the first-shot samples in the second run, owing to the gasgenerated during the second-run molding.

TABLE 1-1 Example 1 Comp. Ex. 1 Comp. Ex. 2 Blend Ratio (A) PC-1 85 85100 (B) PET 15 15 — PBT — — — (C) PTFE 0.5 0.5 0.5 (D) PC-PDMS — — — (E)Silicone-1 4 — 4 Silicone-2 — — — Silicone-3 — — — (F) Talc — — — (G)Elastomer — — — Total Silicone 4.0 0 4.0 Content (wt. %) Evaluation (1)Melt 35 33 22 Flowability: MI (g/10 min) (2) IZOD Impact 45 35 15Strength (kJ/m²) (3) Flexural 2300 2300 2400 Modulus (MPa) (4) Grease1.6≦ 1.6≦ 0.5 Resistance (critical deflection) (5) Flame V-0 V-2 out V-0Retardancy (1.5 mm) (6) Thermal good good good Stability in dwell time(appearance)

TABLE 1-2 Comp. Ex. 3 Comp. Ex. 4 Example 2 Blend Ratio (A) PC-1 85 8585 (B) PET 15 15 15 PBT — — — (C) PTFE — 0.5 0.7 (D) PC-PDMS — — 33 (E)Silicone-1 4 — 2.7 Silicone-2 — — — Silicone-3 — 4 — (F) Talc — — — (G)Elastomer — — — Total Silicone 4.0 4.0 3.0 Content (wt. %) Evaluation(1) Melt 35 35 30 Flowability: MI (g/10 min) (2) IZOD Impact 45 40 55Strength (kJ/m²) (3) Flexural 2300 2300 2300 Modulus (MPa) (4) Grease1.6≦ 1.6≦ 1.2 Resistance (critical deflection) (5) Flame V-0 V-2 out V-0Retardancy (1.5 mm) (6) Thermal good good good Stability in dwell time(appearance)

TABLE 1-3 Comp. Ex. 3 Ex. 4 Ex. 5 Ex. 5 Blend Ratio (A) PC-1 60 60 60 85(B) PET 40 40 — 15 PBT — — 40 — (C) PTFE 2.0 1.2 0.6 0.5 (D) PC-PDMS 300300 100 (E) Silicone-1 — — — 0.3 Silicone-2 — — 4 Silicone-3 — — — (F)Talc — 40 20 (G) Elastomer — — 10 Potassium — — — 0.2 Perfluorobutane-sulfonate Total Silicone 3.0 2.7 3.5 0.3 Content (wt. %) Evaluation (1)Melt 28 26 38 40 Flowability: MI (g/10 min) (2) IZOD Impact 60 15 40 15Strength (kJ/m²) (3) Flexural 2400 3700 3400 2500 Modulus (MPa) (4)Grease 1.0 1.4 1.6≦ 1.6≦ Resistance (critical deflection) (5) Flame V-1V-0 V-0 V-2 Retardancy (1.5 mm) (6) Thermal good good good SilverStability in dwell time (appearance)

Table 1 indicates the following.

(i) The flame retardancy of Comparative Example 1 containing neither thecomponent (D) nor the component (E) is poor.

(ii) The melt flowability and the grease resistance of ComparativeExample 2 not containing the component (B) are poor.

(iii) The flame retardancy of Comparative Example 3 not containing thecomponent (C) is poor.

(iv) The flame retardancy of Comparative Example 4 containing anordinary silicone compound is poor.

(v) The impact strength of Comparative Example 5 containing potassiumperfluorobutanesulfonate is low, and the thermal stability in dwell timethereof is poor.

INDUSTRIAL APPLICABILITY

The polycarbonate resin composition of the invention contains neitherhalogen nor phosphorous, and is highly resistant to flames thoughcontaining a minor additive, and it has good impact resistance, highstiffness, good melt flowability and good chemical resistance.Therefore, the moldings of the polycarbonate resin composition of theinvention are favorable for housing and parts of OA appliances,information appliances, and other electric and electronic appliances forhousehold use and industrial use, and also for automobiles parts, etc.

What is claimed is:
 1. A polycarbonate resin composition, comprising: aresin mixture of (A) and (B): (A) from 50 to 90% by weight of apolycarbonate, and (B) from 10 to 50% by weight of a thermoplasticpolyester, relative to 100 parts by weight of said resin mixture of (A)and (B); (C) from 0.01 to 3 parts by weight of a polyfluoro-olefinresin, and a mixture of (D) and (E); wherein (D) is from 1 to 400 partsby weight of a polycarbonate-polyorganosiloxane copolymer; wherein (E)is from 0.1 to 10 parts by weight of a functional silicone compound, andwherein a silicone content derived from the component (D) and thecomponent (E) falls between 0.5 and 10% by weight of said resincomposition.
 2. The polycarbonate resin composition as claimed in claim1, further comprising (F) from 1 to 50 parts by weight of an inorganicfiller.
 3. The polycarbonate resin composition as claimed in claim 1,wherein the functional silicone compound for the component (E) has abasic structure of a general formula (1): R¹ _(a)R₂^(b)SiO_((4−a−b)/2)  (1) wherein R¹ indicates a functional group, R²indicates a hydrocarbon residue having from 1 to 12 carbon atoms, and aand b are numbers satisfying the relations of 0<a≦3, 0≦b<3, and 0<a+b≦3.4. The polycarbonate resin composition as claimed in claim 1, wherein afunctional group in the functional silicone compound for the component(E) is at least one group selected from the group consisting of analkoxy group, a vinyl group, a hydrogen residue and an epoxy group. 5.The polycarbonate resin composition as claimed in claim 1, wherein afunctional group in the functional silicone compound for the component(E) is a methoxy group or a vinyl group.
 6. The polycarbonate resincomposition as claimed in claim 1, wherein the polyfluoro-olefin resinfor the component (C) is a fibril-forming polytetrafluoroethilene havinga mean molecular weight of at least 500,000.
 7. The polycarbonate resincomposition as claimed in claim 1, wherein the polyearbonate for thecomponent (A) has a viscosity-average molecular weight of from 15,000 to20,000.
 8. The polycarbonate resin composition as claimed in claim 2,wherein the inorganic filler for the component (F) is talc having a meanparticle size of from 0.2 to 20 μm.
 9. Housings or parts of electric andelectronic appliances, which comprise the polycarbonate resincomposition of claim
 1. 10. The polycarbonate resin composition asclaimed in claim 3, wherein the inorganic filler for the component (F)is talc having a mean particle size of from 0.2 to 20 μm.
 11. Thepolycarbonate resin composition as claimed in claim 4, wherein theinorganic filler for the component (F) is talc having a mean particlesize of from 0.2 to 20 μm.
 12. The polycarbonate resin composition asclaimed in claim 5, wherein the inorganic filler for the component (F)is talc having a mean particle size of from 0.2 to 20 μm.
 13. Thepolycarbonate resin composition as claimed in claim 6, wherein theinorganic filler for the component (F) is talc having a mean particlesize of from 0.2 to 20 μm.
 14. The polycarbonate resin composition asclaimed in claim 7, wherein the inorganic filler for the component (F)is talc having a mean particle size of from 0.2 to 20 μm.
 15. A moldingobtained from the polycarbonate resin composition as claimed in claim 1.16. The molding as claimed in claim 15, further comprising (F) from 1 to50 parts by weight of an inorganic filler.
 17. The molding as claimed inclaim 15, wherein the functional silicone compound for the component (E)has a basic structure of a general formula (1): R₁ ^(a)R₂^(b)SiO_((4−a−b)/2)  (1) wherein R¹ indicates a functional group, R²indicates a hydrocarbon residue having from 1 to 12 carbon atoms, and aand b are numbers satisfying the relations of 0<a≦3, 0≦b<3, and 0<a+b≦3.18. The molding as claimed in claim 15, wherein a functional group inthe functional silicone compound for the component (E) is at least onegroup selected from the group consisting of an alkoxy group, a vinylgroup, a hydrogen residue and an epoxy group.
 19. The molding as claimedin claim 15, wherein the polyfluoro-olefin resin for the component (C)is a fibril-forming polytetrafluoroethylene having a mean molecularweight of at least 500,000.
 20. The molding as claimed in claim 15,wherein the polycarbonate for the component (A) has a viscosity-averagemolecular w eight of from 15,000 to 20,000.